Using our api, store and retrieve data with a unique "user name", "password", and key (each of which can be up to 256 characters long) - and DataWamp.us will store it for you. Free. There is no sign up or registration, but this service is public - so if your user name and password are not unique enough, it's liable to be easily read and/or overwritten by anyone. Hey - it's the internet! Hooray!
User names and passwords when used together will serve as a unique "identification". There can be the same user name with separate passwords that will not have access to the same data, and so on. This service is not intended to be secure, and as such, you should assume all data you submit to DataWamp.us to be public!!! However, there is no current way or plan to list user names and password combinations for public browsing.
There is one last hitch: whatever data we receive, we json encode it and store it in a MySQL database. If the encoded string is > 4096 characters, the submission will fail. Otherwise, your data is safe here for as long as I care to keep this project up =] ...should I put up a donation page?